As a beginning investigator at Columbia University, I developed a particular interest in the determinants of recurrent stroke. In preliminary work, I identified dementia as an independent risk factor for long-term stroke recurrence (adjusted RR=2.7) in elderly individuals with ischemic stroke. As part of my MCSDA proposal, I plan to further investigate the relationship between dementia and recurrent stroke. A prospective cohort study is proposed to investigate the following primary hypotheses: (1) dementia after stroke is an independent predictor of recurrent stroke in older individuals hospitalized with acute ischemic stroke, and (2) infarct number and volume, cerebral atrophy, lacunar infarction, and leukoaraiosis are independent neuroradiologic predictors of recurrent stroke, adjusting for dementia status. Secondary aims are to investigate (1) the effect of dementia on the type and extent of diagnostic testing performed after the index stroke to determine the ischemic stroke subtype, (2) the effect of dementia on physician choice of treatment with anticoagulant or antithrombotic medication for secondary prevention, and (3) the effect of dementia on the outcome of disability and death following recurrent stroke. A total of 452 patients with ischemic stroke will be enrolled in this three-year study. Subjects will be drawn from the ongoing Stroke and Aging Research Project (SARP, RO1-NS26179). Dementia assessment will be based on the results of neuropsychological and functional testing performed three months after stroke. Brain imaging obtained during hospitalization for stroke will be analysed using quantitative regions of interest volumetry and threshold-based segmentation methodology. Follow-up data regarding symptomatic recurrent stroke over the study period will be gathered using semi- annual telephone calls, annual in-person interviews and neurologic examinations, and continuous surveillance of admissions to our medical center. This award will enable me to develop the expertise necessary for an independent research career by allowing me to (1) pursue courses in the School of Public Health towards a Masters degree, (2) learn new skills in the area of quantitative brain imaging, (3) collaborate with neuroepidemiologists in the Sergievsky Center, (4) continue my participation in SARP, and (5) acquire the necessary experience and data to provide the basis for future independent investigator awards (RO1 or R29).